1. Field of the Invention
This invention relates to transparent image recording materials suitable for use in xerographic and electrographic copying devices. Specifically, it relates to coatings for transparencies having specific physical properties for use in overhead projectors.
2. Description of the Art
Many different types of transparent image receptive sheets or receptors are known in the art. Typically, these transparent sheets are comprised of thin oriented films made from one or more organic resins such as polyesters, and overcoated with an image receptive layer on one major surface. Such sheets can be used as receptors in different printing and imaging methods such as thermal transfer printing, ink-jet printing and xerographic or electrographic copying, to produce transparencies suitable for use with commercially available overhead projectors.
In the formation and development of xerographic images, a toner composition comprised of resin particles and pigment particles is generally applied to a latent image generated on a photoconductive member. The image is then transferred to the image receptive sheet and affixed there by the application of heat, pressure, or a combination thereof.
Japanese Patent 1289838A discloses a composite polyester film having a cover layer comprising a concentration of sulfonic acid or sulfonate. The composite film is taught to eliminate "pile traveling" (simultaneous feeding of more than one sheet), and to yield excellent transparency flatness and toner adhesion.
U.S. Pat. No. 5,104,721 discloses a medium for electrophotographic printing or copying, especially laser electrophotography comprising a polymeric substrate coated with a polymeric coating having a Tukon hardness of about 0.5 to 5.0 and a glass transition temperature of about 5.degree. to 45.degree. C. The coating comprises at least one pigment which provides a coefficient of static friction of from 0.20 to 0.80 and a coefficient of dynamic friction of from 0.10 to 0.40. The polymer employed in the coating can contain thermosetting or thermoplastic resins, and preferably aqueous acrylic emulsions such as Rhoplex.TM. resins from Rohm and Haas. Improved image quality and toner adhesion is disclosed.
U.S. Pat. No. 5,104,731 discloses a dry toner imaging film media having good toner affinity, anti-static properties, embossing resistance and feedability through electrophotographic copiers and printers. The media comprises a polymeric substrate coated with an antistatic matrix layer. The matrix layer has blocking resistance at 78.degree. C. after 30 minutes and a surface resistivity of from about 1.times.10.sup.8 to about 1.times.10.sup.14 ohms per square at 20.degree. C. and 50% relative humidity. The matrix contains one or more thermoplastic polymers having a T.sub.g of 5.degree. C. to 75.degree. C., and at least one crosslinked polymer which is resistant to hot roll fuser embossing, at least one of the polymers being electrically conductive.
U.S. Pat. No. 4,480,003 discloses a transparency film for use in plain paper electrostatic copiers. A first surface of a flexible, transparent, heat resistant polymeric film is coated with an image receiving layer, preferably, a toner-receptive, thermoplastic, transparent polymethylmethacrylate polymer containing dispersed silica particles. The second major surface of the film base has a coating of non-migratory electrically conductive material, preferably a polymer derived from the reaction of pyridine and 2 amino-pyridine with partially chloromethylated polystyrene. A primer coating between the polymeric film base and the layer of conductive material is preferred to provide suitable adhesion. A protective coating to control abrasion, resistance, roughness and slip properties is also preferred. It is disclosed that the sheet can be fed smoothly from a stack and produces clear background areas.
U.S. Pat. No. 4,869,955 discloses an element suitable for preparing transparencies using an electrostatic plain paper copier. The element comprises a polyethylene terephthalate support, at least one subbing layer coated thereon and, thereover, a toner receptive layer comprising a mixture of an acrylate binder, a polymeric antistatic agent having carboxylic acid groups, crosslinking agent, butylmethacrylate modified polymethacrylate beads and submicron polyethylene beads.
U.S. Pat. No. 4,956,225 discloses a transparency suitable for electrographic and xerographic imaging comprising a polymeric substrate with a toner receptive coating on one surface thereof which comprises blends selected from a group consisting of: poly(ethylene oxide) and carboxymethyl cellulose; poly(ethylene oxide), carboxymethyl cellulose and hydroxypropyl cellulose; poly(ethylene oxide) and vinylidene fluoride/hexafluoropropylene copolymer; poly(chloroprene) and poly(alpha-methylstyrene); poly(caprolactone) and poly(alpha-methylstyrene); poly(vinyl isobutylether) and poly(alpha-methylstyrene); poly(caprolactone) and poly (.alpha.-methylstyrene); chlorinated poly(propylene) and poly(.alpha.-methylstyrene); chlorinated poly(ethylene) and poly(.alpha.-methylstyrene); and chlorinated rubber and poly (.alpha.-methylstyrene). Also disclosed are transparencies with first and second coating layers.
U.S. Pat. No. 5,229,188 discloses a transparent laminate film for full color imaging comprising two transparent resin layers. The first resin layer is heat-resistant, and the second resin layer must be compatible with a binder resin constituting the toner to be used for color image formation. The second resin layer has a larger elasticity than that of the binder resin of the toner at a fixing temperature of the toner. The second resin can be of the same "kind" i.e., type, e.g., styrene-type or polyester type, as the toner binder, as long as the resins differ in storage elasticity.
U.S. Pat. Nos. 5,026,782 and 5,147,940 disclose opaque polymer particles comprising a non-swellable core polymer, covered at least in part, by a shell polymer. The core polymer can be made of vinyl halide with a T.sub.g of at least 50.degree. C. The polymer is disclosed for use in the manufacture of paints, paper coatings and films, especially latex binder compositions.
U.S. Pat. No. 5,216,044 discloses a synthetic resin emulsion with solid core-shell polymer particles having a diameter of from 0.1 to 5.0 .mu.m which spontaneously become porous in a dry state. A process for producing the synthetic resin emulsion comprises the step of preparing the core particles, e.g., by emulsion polymerization of an acrylate ester an another monomer copolymerizable therewith, and then forming a shell of polymer which is more resistant to hydrolysis than the internal core particle. The fine polymer particles of this synthetic resin emulsion save weight and improve hardness, abrasion resistance and thermal resistance. The particle can also be used for an additive to various compositions, paper, metals, plastics, fibers and cloth.
U.S. Pat. No. 5,254,403 discloses a recording sheet having a substrate and an image receiving layer comprising a mixture of a latex-forming polymer, a polysaccharide and a polymer containing oxyalkylene monomers. The recording sheets are disclosed to exhibit high optical density, minimum intercolor bleeding, and minimum blocking at 50% to 80% humidity and temperatures of over 50.degree. C.
U.S. Pat. No. 4,497,917 discloses a latex composition comprising core-shell polymer particles where the core has a T.sub.g greater than 70.degree. C. and the shell has a T.sub.g of from 25.degree. C. to 60.degree. C. Because of the relatively low T.sub.g shell, the particles can coalesce sufficiently to form continuous layers under the conditions usually employed to form coatings on photographic film bases and layers. Preferred latex compositions comprise core polymers 80% to 95% polymerized .alpha.,.beta.-ethylenically unsaturated monomer, and shell polymers also of polymerized .alpha.,.beta.-ethylenically unsaturated monomers.
U.S. Pat. No. 4,891,285 discloses an image copy film comprising a film substrate, an image-receiving layer on a surface of the substrate and a toner image layer on the surface of the receiving layer remote from the substrate. The receiving layer comprises of a terpolymer comprising a vinyl halide, a vinyl ester of a saturated aliphatic carboxylic acid, the molecule of which contains from 2 to 6 carbons; and a functional group containing ethylenically-unsaturated termonomer. This copy film has improved toner adhesion and superior resistance to abrasion and erasure.
U.S. Pat. No. 5,212,008 discloses a recording sheet comprising a substrate, a first coating and a second coating thereover. The first coating comprises a polymer, a crosslinking agent therefor, and a catalyst. The second coating comprises a binder and a quaternary amino compound.
U.S. Pat. No. 5,254,403 discloses a recording sheet comprising a substrate and an image receiving layer comprising a mixture of a latex-forming polymer, a polysaccharide and a polymer containing oxyalkylene monomers. The recording sheets exhibit high optical density, minimum intercolor bleeding, and minimum blocking at humidities of 50% to 80% at temperatures of over 50.degree. C.
U.S. Pat. No. 5,208,211 discloses an image receiving sheet including a transparent support and an overcoat layer. The overcoat layer includes a thermoplastic resin which has a fluidification initiation temperature lower than that of a toner for image formation to be employed or that of a resin for use in said toner, and is white and opaque from being in a porous state.
U.S. Pat. No. 5,289,245 discloses a recording material for use in electrography in which a toner image is formed on the recording material and then fixed thereto by the applying pressure to the toner image using a fixing rotatable member coated with a releasing agent. In one embodiment, the recording material has a base layer, a first resin layer having greater compatibility with the toner than the base layer, and a second resin layer containing a releasing agent absorber. In another embodiment, the compatible resin layer contains the releasing agent absorber. In an embodiment for color imaging, the resin layer containing the releasing material absorber is provided under the compatible layer.
U.S. Pat. No. 5,266,383 discloses a recording medium comprises a surface layer composed mainly of aluminum oxide particles and a lower layer having ink absorptivity, this lower layer being formed of paper. The aluminum oxide particles have particle sizes of 5 .mu.m or less. This can give an image that is high in density, has excellent ink absorptivity and color forming characteristics, with little deterioration due to in-room decoloration.
U.S. Pat. No. 5,330,823 discloses a recording sheet comprising a substantially transparent substrate, a binder polymer coated thereon, and particles of an antistatic component present on at least the surface of the binder polymer coating. Alternately, a transparent recording sheet is provided wherein both an antistatic component and an anti-slip component are contained in a single coating layer of the sheet.
U.S. Pat. No. 5,308,389 discloses a water-based composition for forming a flexible film on metals and other surfaces, comprising a water-dispersible polyurethane elastomer, an anti-corrosive agent, a thickener, a dispersing agent and an antifreeze agent. This provides a non-yellowing high gloss film which quickly becomes tack-free.
U.S. Pat. No. 5,183,504 discloses an aqueous metallic coating composition comprising 1) an aqueous acrylic resin of from 5% to 40% by weight of amide group containing ethylenic monomers, 3% to 15% by weight of acid group containing ethylenic monomers, 10% to 40% by weight of hydroxyl group containing ethylenic monomers and the balance of other ethylenic monomers and a portion of the acid group is neutralized, and 2) a specific urethane oligomer dispersion containing a primary and/or secondary polyamine.
U.S. Pat. No. 5,141,983 discloses an aqueous coating composition comprising 1) an aqueous polyurethane resin obtained by reacting a diisocyanate and glycols containing a carboxylic acid group containing glycol to prepare an urethane prepolymer, neutralizing the urethane prepolymer and subjecting the neutralized urethane prepolymer to chain extension with a hydrazine derivative; and 2) an aqueous dispersion of an acrylic copolymer whose constituent monomers contain carbonyl group containing monomer or an amido group containing monomer in an amount of at least 0.5 parts by weight per 100 parts by weight of total polymerizable monomers. The weight ratio in terms of solid content, of 1) to 2) is 100/5 to 5/100. This composition can be used, among other things, as a wetting agent, a thickener and/or rheology controlling agent, or a film formation aid.
U.S. Pat. No. 5,156,904 discloses an oriented polymeric film in-line coated with polyethyleneimine before heat setting of the film. When used to make a laminate with other polymers such as polyethylene or ionomer type polymers, this film shows no signs of delamination between the polymeric film and the extrusion coated polymer after 2 hours in water at 121.degree. C. at 15 psi. Polyethylene terephthalate is preferred.
U.S. Pat. No. 5,212,273 discloses crosslinked polymeric microparticles obtained by polymerization of a mixture of ethylenically unsaturated monomers being substantially free of monomers containing polar groups. At least one of said monomers is a polyethylenically unsaturated crosslinking monomer free of oxyethylene groups. The crosslinked polymeric microparticles are prepared by aqueous emulsion polymerization techniques in the absence of polyester emulsifier, and are separated from the aqueous polymerization medium and converted into organic medium by azeotropic distillation. The microparticles are useful in organic solvent-based high solids coating compositions and can be used in color coats, clear coats or composite color-clear coatings. The microparticles are disclosed to improve the sag resistance and the metallic pigment pattern control of the coating and do not detract from the overall desirable properties of the coating.
U.S. Pat. No. 5,310,591 discloses a transparent image-recording sheet suitable for use in a plain paper copier comprising a transparent backing having two major surfaces, said sheet having a machine direction, and a transverse direction, at least one of the major surfaces having coated thereon a transparent water-based toner-receptive coating comprising: a) from about 65 to about 99.9 parts of an imageable polymer; b) from about 0.1 to about 15 parts of at least one polymeric particle having a mean particle size ranging from about 1 .mu.m to about 15 .mu.m, and c) from 0 to about 20 parts of an antistatic agent, the toner-receptive coating being coated onto the trans-parent backing at a time during manufacture of the backing selected from the group consisting of a) before any orientation of said film, and b) after uniaxial orientation in the machine direction.
U.S. Pat. No. 5,310,595 discloses a transparent image-recording sheet suitable for use in a plain paper copier, comprising a transparent backing having two major surfaces, said sheet having a machine direction, and a transverse direction, at least one of the major surfaces having coated thereon, a transparent water-based toner-receptive coating comprising an imageable polymer formed from at least one monomer selected from the group consisting of bicyclic alkyl(meth)acrylates, aliphatic alkyl (meth)acrylates having from about one to about 12 carbon atoms, aromatic (meth)acrylates, and a polar monomer having the formula: ##STR1## wherein R is hydrogen or methyl, R.sub.1 and R.sub.2 may be hydrogen, alkyl groups having up to about 12 carbon atoms, preferably up to about 2 carbon atoms, or the quaternary cationic salts thereof, at least one long chain polymeric particle having good antifriction characteristics and optionally, an antistatic agent selected from the group consisting of cationic agents, anionic agents, fluorinated agents, and non-ionic agents.
The present inventors have now discovered a class of core/shell latex polymers that can be coated from an aqueous medium in the form of a latex onto a substrate, to form a transparent film having an image-receptive coating useful for producing an image on various copiers using a variety of toners with differing binder resins, with excellent toner adhesion, good image quality and good feedability.